1. Technical Field
The present invention relates to a content providing apparatus and a content providing method that can be applied, for example, to the distribution of music and videos via the Internet. In the present invention, single stream content is divided into a plurality of parts in a time-series manner, and a first part is transmitted via stream distribution, whereas remaining parts are transmitted via buffering distribution such that decoding of a receiver's side can be started upon the end of decoding an immediately preceding part, whereby the stream content is distributed with a high reliability and latency can be reduced remarkably as compared to that in the conventional art.
2. Background Art
Conventionally, to distribute information such as music, films, etc. whose content changes with time (hereinafter called stream content), it is designed to use a method of providing stream content while its data is being received (hereinafter called stream distribution) and a method of providing a user with stream content after its data is temporarily buffered (hereinafter called buffering distribution).
That is, in the stream distribution, as shown in FIG. 1, a transmitter's side transmits stream content to a client at a transfer rate that is substantially the same as a reproduction speed (FIG. 1 (A)), and a receiver's side buffers the received data in an amount large enough to decode the stream content (FIG. 1 (B)) for sequential decoding (this process on the receiver's side is called stream reception as corresponding to the stream distribution). In the case of this method, the stream content transmitted by the transmitter can be reproduced only to a very small delay time required for data transmission and decoding (FIG. 1 (C)), whereby the latency between the start of receiving the stream content and the start of actually reproducing it can be reduced, thereby allowing the stream content to be provided smoothly.
By contrast, in the buffering distribution, as shown in FIG. 2, a transmitter's side transmits stream content at a rate irrelevant to the reproduction speed (FIG. 2 (A)). A recipient receives the stream content, buffers all the received stream content (FIG. 2 (B)), and thereafter decodes the buffered stream content to provide a user with the decoded stream content (FIG. 2 (C)) (this process on the receiver's side is hereinafter called buffering reception as corresponding to the buffering distribution). In the case of this method, there is a shortcoming that a relatively long time interval is required between the start of receiving the content and the start of actually reproducing it. However, in the case of this method, all the stream content is received and buffered in advance prior to its reproduction, and this allows an error recovery technique, such as error correction or retransmission request processing in TCP/IP, to be applied, whereby the stream content can be distributed with a correspondingly higher reliability.
In the buffering distribution, it is so designed that single stream content is decomposed into a plurality of parts to be transmitted sequentially, thereby reducing the latency between the start of receiving the stream content and the start of actually reproducing it.
That is, in the case of this method, as shown in FIG. 3, a transmitter's side divides single stream content into, for example, four parts A to D in a time-series manner, and transmits these parts A to D sequentially (FIG. 3 (A)). In response thereto, a receiver's side receives and buffers these parts A to D, and, upon completion of receiving one part, starts reproducing this part. Thus, it is so designed that after having buffered the first part A, the receiver's side starts decoding a part whose reception is completed while buffering another part, thereby reducing the latency (FIGS. 3 (B) and (C)).
Thus, the buffering distribution has merit in that stream content can be distributed with a high reliability, but it does involve the problem of generating latency. For this reason, a user who has requested stream content cannot listen to a demonstration of the content during the latency period. Incidentally, as explained with reference to FIG. 3, even when single stream content is divided and distributed as a plurality of parts, the latency does exist before reception of the first part is completed.